31311-A
Holding a bearing marked SKF 31311 or NSK 30311D or NTN 30311D? Ours is 31311-A — the same seat size, the same type and the same sealing and clearance design.
What this bearing is
31311-A is a tapered roller bearing, execution: open. The manufacturer's cross-reference catalogue confirms full interchangeability for 22 designations, including SKF 31311, SKF 31311J2/Q, NSK 30311D.
Designation equivalents
Before you replace it
This is a dimensional and design equivalent: the same seat size, the same bearing type and the same sealing and clearance design. It is not the same product — load ratings, tolerance class and grease may differ between manufacturers. For duty close to the limits or a critical application, check the datasheet of the specific design.
The same seat in another execution
These items share the mounting size and have cross-reference tables of their own. They differ in sealing, clearance or cage — exactly what decides how the bearing behaves in the seat.
Where these equivalents come from
The base number of a standard bearing is an ISO standard — 6205 is 6205 at every manufacturer. Only the suffixes describing the design differ, and those are what we translate: shields, contact seals, cage and radial clearance. Designations that mean different things at different makers are deliberately omitted.